Use of Hemoglobin A1c as An Early Predictorof Gestational Diabetes Mellitus

Abstract

Gestational diabetes mellitus (GDM) is a prevalent and potentially serious condition that may lead to adverse effects in both mothers and neonates (ADA, 2014; Renz et al., 2015). It is associated with preeclampsia, increased caesarean rates, and macrosomia (Metzger et al., 2008). Gestational diabetes mellitus (GDM) affects approximately 7-17% of all pregnancies and has been recognized as a significant risk factor to neonatal and maternal health (Kenna et al., 2016). Within the last 20 years, the prevalence of gestational diabetes mellitus (GDM) has been reported to be increasing worldwide in correlation with ethnic and geographic variations. The actual prevalence of GDM throughout all of Greenland remains unknown (Pedersen et al., 2016). The detection and treatment of GDM reduce the risks for the mothers as well as for the babies (Hartling et al., 2013). Although the risks of complications in the presence of GDM are well established, there is considerable controversy regarding its diagnosis (Waugh et al., 2010). Traditionally, the OGTT has been the test of choice for this condition. It can be preceded by a screening strategy such as fasting glycemia (FG) or a glucose load test. However, there are still divergences as to the OGTT cut-offs which should be used for the diagnosis of GDM and also a recent review concluded that the evidence are insufficient to permit assessment of which strategy is best to diagnose GDM (Farrar et al., 2015). In 2010, the American Diabetes Association (ADA) included HbA1c test as a diagnostic criterion for diabetes (DM) in the general population. The cut-off of HbA1c ≥48 mmol/mol (6.5%) was established for the diagnosis, and was endorsed by the World Health Organization (WHO) in 2011 (ADA, 2015). This cut-off has high specificity in diagnosing DM (Kramer et al., 2010). However, HbA1c and glucose tests show very weak agreement, and it seems that these two tests may identify different populations of patients (Cavagnolli et al., 2011). However, the Hyperglycaemia and Adverse Pregnancy Outcomes (HAPO) study showed that HbA1c measurements, similar to glycemia levels, were significantly associated with all adverse outcomes, and higher levels of maternal HbA1c were related to a greater frequency of adverse outcomes (Lowe et al., 2012). This prospective cohort study was performed to assess the accuracy of HbA1c in prediction of gestational diabetes in first trimester. It included women during child bearing period (18-35 years old) with singleton pregnancies and patients receiving antenatal care during their first trimester will be included regardless of prepregnancy GDM risk. Patients with multiple gestations, medications that affect insulin and glucose levels or medical conditions that influence Hb-A1c and its measurement were excluded from the study. After approval of ethical committee and obtaining informed consents, all women participating were subjected to counseling about all the steps of the study and will have the procedure fully explained. Careful history was taken regarding personal, menstrual, obstetric, medical and surgical histories. Complete physical examination was done to exclude any disorders may interfere with the results. Investigations such as U/S to ensure that they comply with the inclusion and exclusion criteria. Gestational age was calculated from the last menstrual period and confirmed by ultrasound measurement during the first trimester of pregnancy.